Gas puating silicone treated fibers



Aug. 12, 1958 F. E. DRUMMOND 2,847,322

GAS PLATING SILICONE TREATED FIBERS Filed June 23, 1955 Fig] Fiber extrusion F/Zwr base Spin/rare! 2 Healing 28 30 Heat resistant malarial Heal sensitive fiber INVENTOR FOLSOM E, DRUMMOND a B Ida/6m ATTORNEYS GAS PIJATING SILICONE TREATED FIBERS Folsom'E. Drummond, Washington, D. C., assignor to The Commonwealth Engineering Company of Ohio, Dayton, Ohio, a corporation of Ohio Application June 23, 1955, Serial No. 517,647

Claims. (Cl. 117-71) This invention relates to metallized heat-sensitive filaments, fibers, and the like, and more particularly to a method of treating such fibers whereby the same can be readily gas plated to provide a metallized fiber.

The invention is also adapted for producing metallized fabrics or the like articles which are woven or felted from heat-sensitive filaments which have been metallized in accordance with'this invention.

Various methods and materials have been used heretofore in the treatment of fibers and fabrics to produce a product having a desirable characteristic property or com bination of properties, as desired. Various liqiud coating and impregnating compositions'have been used to treat fibers and fabrics to coat and fill the same and produce a product having the desired characteristic properties.

Different fibers and fabrics have also been coated using metal particles or pigments dispersed in'liquid vehicles. Application of such coatings to fibers andfabric woven therefrom has been achieved by immersion of the material in a bath of the composition and drying or curing 'to produce a finished product. In other instances the metal containing composition is applied by spraying so as to form a product having a metal-like surface or coating film. Such coating films, however, are more in the nature of a sheath about the fibers or fabric and tend to render the fiber or fabric stiff and unmanageable so that the finished product largely loses its textile characteristic properties.

The present invention is designed to overcome these disadvantages and to provide a metallized fiber,'filament, or fabric which has the characteristic properties ofithe metal usedto treat the material, yet retains, at least to a large extent, its original characteristic textile or fiberlike properties. The invention is especially useful in metallizing fibers or fabric which is heat-sensitive by the application of heat-resistant silicone resin to provide a fiber which will withstand gas plating temperatures.

Although the invention will be described as applied primarily to a fiber or filament, it is intended thatthe inventionwill include like treatment of fabrics or articles woven or felted, or otherwise fabricated which are made from various type fibers or filaments which tend tosoften and deteriorate when'it is attempted to gas plate the fibers at temperatures required to carry out theheatdecomposable metal-bearing compound. The invention, accordingly, contemplates the treatment of one-.or more fibers orfilaments whereby the same can be gasplated without injury to the fibers and produce a metallized fiber product.

In accordance with the broad concept of the invention, fibers of difierent type or mixture of such fibers indiv-idually or collectively, are given a protective coating-of a flexible heat-resistant silicone coating. Thereafter the resultant coated fiber is treated with a heat-decomposable gaseousmetal compound or mixture thereof to produce the desiredmetallized fiber product. In each instance the gaseous metal compound employed and the condi tions of treatment may be varied, depending upon'the rates Patent 0 desired metallized fiber product and the nature of the fiber being treated.

Various heat-sensitive fibers may be treated in accordance with this invention, such as vegetable fibers,'e. g., cotton, hemp, jute, etc.; animal fibers, e. g., silk, wool, and anmial hair or fur and the like which may be classified as essentially proteins, as well as semi-synthetic fibers,

e. g., rayons which are made from cellulose or its derivatives, such as cotton linters, wood pulp, etc.; manufactured protein fibers, e. g., casein and vegetable proteins extracted from various plants, etc., and synthetic fibers such as belong to the vinyl or vinylidene class as Vinyon, Saran, Velon, Dynel, Acrilan, Orlon and polyamide type such as Nylon, Terylene, Dacron and the like, and suitable mixtures thereof, for example, rayon and cotton; acetate rayon and cellulosic fibers; rayon and wool,.nylon and wool, etc.

Themetallization of the fibers is accomplished in accordance with this invention, preferably during the spinning of the filament or fabrication of the fibrous product into a thread or fiber to produce a product wherein the fibers are individual filaments containing uniform dispersions of metal particles.

In the case of wet spinning, for example, where a solution of a higher molecular weight film and fiber-forming material is wet spun into a coagulating solution from a spinneret and the resultant fiber taken up on a Godet wheel and thence onto a windup bobbin or spool, the fiber before passing to the windup bobbin or spool, and preferably 'while being taken up on the Godet wheel is subjected to treatment to provide the same with a protective coating which is resistant to heat, and which is flexible and durable. subjected to gas plating to thus impregnate and coat the filaments with the desired metal.

In dry spinning of fibers or filaments, as by forcing a solution of a resin or film-forming material dissolved. in solvent through a suitable die into a heated gaseous medium which removes the solvent and precipitates therein so that it can be drawn out into a continuous length thread or filament, the fiber is subjected to a spray or dip-coat of the heat-resistant coating composition prior to gaseous metal treatment. Preferably the heat resistant coating is applied immediately after the removal of the solvent during the production or manufacture of the fiber.

The treatment of the fibers to render them heat-resistant may be suitably combined with thesolvent removal operation whereby the solvent is removed and concurrently replaced with heat-resistant resin which is brought into intimate contact with the fiber.

Where the solvent vapor mixture tends to interfere v with the protective coating application, the process is modified to provide for removal of the solvent before the fibers are subjected to application of resin such as silicones.

In the production of fibers by the application of heat and extrusion, the fiber is extruded from the die and then passed through a solution of resin then into a chamber in which there is circulated a heat-decomposable gaseous metal compound or gaseous mixture containing the same to effect 'the'metallization of the fiber while it is still in aheated and semiplastic condition. In this manner, the heat required for softening and extruding the resin or thermoplastic material through the die is used to assist in the application of a heat-resistant coating as Well as thegaseous metal decomposition and metallization operation.

The'heat-resistant coating composition applied to the heat-sensitive fibers preferably comprise organo-silicon compounds commonly known as silicones. Silicone rubbers or resins in the cured state have been found Patented Aug. 12, 1958 The fiber, thus protected, is then eminently suitable because they can be exposed to elevated temperatures without deterioration and remain flexible so that the treated fibers do not become stifi and unmanageable. A particularly useful silicone which remains flexible and heat-resistant is methyl polysiloxane convertible to a solid state containing 0.1 to 5% by Weight of isopropyl benzene hydroperoxide.

Suitable siloxanes comprise copolymers of monophenylsiloxane, monomethylsiloxane, (ii-methyl siloxane, diphenylsiloxane and phenyl methylsiloxane, preferably at least 50% of the groups substituted on the silicon being methyl. Such resins can withstand a temperature as high as 315C. without damage. A water white silicone oil which may be used to coat the fiber, before subjecting it to gas plating, is methyl silicone. It has a high resistance to oxidation, corrosive salt solution and mineral acids. If a harder film is desired, methyl silicone oil may be applied and then polymerized by heating to from 200 to 400 F. for several minutes. The heat-resistant resin coating provides a strong adherent bond between the silicone and the metal plating which is applied thereon.

Fibers or filaments may also be impregnated and coated with a solution of an organopolysilane-polysiloxane resin and air dried.

Various methods may be employed for applying the organo-silicon compound onto the fibers or filaments to be metallized. For example, if the silicon compound is a solid it may be comminuted and dusted on the fibers, fabric or the like to be gas plated, or if the compound is a liquid it may be applied to the fibres by dipping, coating, spraying or atomized and applied onto the fibers. Blends of silicones may also be used when it is desired to vary the viscosity of the composition to facilitate its application to the fibers or filaments to be metallized by gas plating.

For carrying out the gaseous metal deposition, different heat-decomposable gaseous metal compounds may be used, for example, gaseous metal carbonyls, metal hydrides, metal alkyls, metal halides, and also nitroxyl compounds, nitrosyl carbonyl, and the like. Metal compounds of the carbonyl type which are useful are carbonyls of nickel, iron, chromium, molybdenum, cobalt, and mixed carbonyls.

Illustrative compounds of other groups are the nifl'oxyls, such as copper nitroxyl; nitrosyl carbonyls, for example, cobalt nitrosyl carbonyl; hydrides, such as antimony hydride, tin hydride; metal alkyls, such as chromyl chloride; and carbonyl halogens, for example, osmium carbonyl bromide, ruthenium carbonyl chloride, and the like.

The compounds each have a different temperature of decomposition. The decomposition, however, generally takes place slowly at lower temperature and increases as the temperature is raised through a particular range. For example, nickel carbonyl starts to decompose slowly at about 170 F. and thereafter decomposition continues during the time of heating upward to 375 F. to 380 F. Many of the metal carbonyls and hydrides may be effectively and efiiciently decomposed at a temperature and range of 300 F. to 450 F. The gaseous metal compound used in each instance depends upon the melting point of the fiber being treated and the metal desired to be deposited on the fibers. Generally, the working temperature, using metal carbonyls, lies in the range of about 300 F. to 425 F. By pretreating the fibers with a silicone, the same is made more heat-resistant so that gas plating can be carried out using heat-decomposable metal bearing compounds which otherwise could not be employed.

In carrying out the gaseous metal decomposition in accordance with the invention, the gaseous metal compound is directed into a chamber wherein it is heated to its decomposition temperature and brought in contact with the silicone coated fiber. The fiber or filament is preferably continuously moved through the gaseous deposition chamber and the amount of metal deposited in the fiber is controlled by regulating the time in which the fiber is subjected to the gaseous plating operation.

The invention will be more particularly described with respect to dry spinning and plastic extrusion methods of producing the fibers, but it will be understood that the invention is adapted also for Wet spinning as aforementioned.

The invention is illustrated in the accompanying drawings, wherein Figure 1 is a diagrammatic view illustrating a method of treating extruded filaments or fibers whereby the same are given a spray coating of silicone prior to gas plating to metallize the filaments;

Figure 2 is a similar diagrammatic view illustrating a method of treating filaments drawn from a spinneret with silicone resin, prior to gas plating the same, by passing the filament from the spinneret into a bath of silicone resin to provide it with a heat protective coating; and

Figure 3 is an enlarged view in cross-section depicting the finished metallized heat-sensitive fiber or filament and illustrating the multi-layer structure.

Referring to the drawings, and more particularly to Figure 1, the reference character 10 designates an extrusion cylinder filled with heat sensitive resin plastic 11 which is extruded in the form of filaments 12. Spray nozzle means 13 which are suitably supplied with silicone oil or resin spray coat the extruded filaments prior to their passage to gas plating chamber 14.

Heat is applied to the silicone coated filaments by the electrical resistance heating coils 15. The heatdecomposable gaseous metal compound or mixture of the same with inert carrier gas is admitted to the plating chamber 14 through an inlet conduit 16, and Waste gases are suitably discharged therefrom through the outlet pipe 17. Metallized filaments 18 are withdrawn from the gas plating chamber 27 where they are gas plated with metal. Metallized fibers 28 as drawn from the gas plating chamber are suitably stored on a roll 30.

The heat sensitive filaments or fibers, as illustrated in Figure 3 are made up of the filament 32 as the core or base, an intermediate layer of heat resistant silicone material and outer layer 34 of metal gas plated thereon to provide a flexible metallized fiber.

In the preparation of films, fibers, rods and other shapes, by the dry spinning process, the solution of resin or the like high molecular weight fiber-forming material is forced through a suitable die into a gaseous medium which removes the solvent and precipitates the resin as a continuous thread or fiber. Thereafter the fiber is treated with silicone such as methyl silicone or high molecular weight alkylated siloxy composition in which a substantial portion of the silicon atoms are attached to two carbon atoms.

The metallizing method for treating heat-sensitive fibers as described is especially useful in the preparation of synthetic fibers and semi-synthetic fibers, and such as are produced by wet or dry spinning, or heat extruded to form a thread or fiber.

For example, the invention is useful in the production of fibers of acrylonitrile polymers, such as polyacrylonitrile and up to 20% of other copolymerizable olefinic monomers, e. g., vinyl acetate, vinyl pyridine, methacrylonitrile, vinylidene chloride, and esters of acrylic and methacrylic acids. In the preparation of this type of fibers by dry spinning, the practice generally involves the volatilization of high boiling solvents such as N,N-dimethylformamide, ethylene carbonate, N,N- dimethylacetamide and butyrolacetone, and the like, as used to form a solution of the fiber-forming resin. These ,solvents often cause discoloration of the fiber unless the temperature is carfully controlled.

The process of the present invention permits controlled heating and removal of the solvent to be efiected during or immediately following the spinning and silicone treatment of the fibers, and allows for metallization of the fiber at much higher temperatures than possible heretofore. The hot gasses, during gaseous metal deposition, may thus be exposed to the fiber for a time sufiicient to remove any volatile solvent remaining and produce a flexible silicone protected metallized fiber. For example, in the preferred practice, the metallization operation may be completed in a few seconds, and generally less than a minute, depending of course, on the amount of metal to be applied to the silicone treated fiber. The metallization preferably is carried out as soon after the spinning and removal of the solvent and application of the silicone as possible. In the case of extruded fiber, the heat of the fiber as it is extruded from the die is used to assist in the carrying out of the silicone pretreatment and gaseous metal deposition to produce a metallized fiber. This is an economical advantage.

While the process is adapted for continuous operation, e. g., the continuous drawing of the fiber from the spinning and extrusion unit at a substantially uniform speed, the process may be readily adapted for discontinuous operation if desired.

In the preferred practice of carrying out the process, the fiber as it comes from the spinneret or extrusion die and while heated to a temperature between 250 F. and 450 F., depending upon the fiber being formed, the filaments or strands making up the thread or continuous length fiber are immediately sprayed with heat-resistant silicone as described and then subjected to a decomposable gaseous metal compound. Employing, for example, nickel carbonyl which decomposes in this temperature range, metallic nickel particles are deposited on and in the filaments. A metallized nickel fiber or thread is thus produced. Similarly, other metal carbonyls, hydrides or the like heat-decomposable metal compounds as aforementioned may be used to produce a particular metallized fiber. Fibers and filaments having a relatively low melting point and are easily damaged by temperatures ordinarily used for gaseous metal plating may be thus protected sufficiently to permit gas plating of such fibers.

The gaseous metal compound used in each instance will depend upon the fiber or filament being metallized and methods of fabrication.

It will be understood that while the invention is described with particular reference to dry spinning and extrusion methods for forming the fiber, the method is readily adapted for treating wet spun, felted or otherwise built-up fibers or filaments and which may or may not be woven or felted together.

The invention is intended to include various methods of forming the fiber in which the fiber is drawn along and siliconized prior to being subjected to gaseous plating to produce the finished metallized fiber.

In the process a stream of hot gaseous metal is brought into direct contact with the heated siliconized fiber at temperatures which-bring about decomposition of the gaseous metal compound to cause deposition of the metal in very fine particles on and into the interstices of the fiber or filament. The gaseous atmosphere may be formed by mixing inert gas with the vapors of a volatile metal compound or by atomizing a liquid metal compound into a blast of hot inert gas such as carbon dioxide, nitrogen, helium or the like. Such inert gases may be used as a carrier medium for the gaseous metal compound. Hydrogen may also be used as well as oxygen so long as the gas does not have any deleterious efiect on the siliconized fiber being metallized.

Air or inert gas may be used for cooling the fibers after the metallizing operation; as an inert gas, carbon dioxide may be used. Also, mixturesof air with other diluting '6 gases may be employed if desired as a cooling medium.

It will be further understood that the proportion of materials and details of treatment and conditions of operation may be modified according to the particular fiber being treated and the gaseous metal compound used without departing from the spirit and scope of this invention as more particularly definedin the appended claims.

What is claimed is:

1. A method of producing gas plated metallized heatsensitive fibers which comprises heating a fiberforming thermoplastic resin to melt the same, subjecting said melted resin to extrusion to form a fiber of continuous length, applying a heat-resistant silicone resin onto said extruded fiber, and subjecting the extruded and silicone resin treated fiber to a heat-decomposable gaseous metal compound, said gaseous metal compound being brought in contact with said extruded fiber while heated to a. temperature to cause decomposition of said gaseous metal compound and deposition of the metal constituent.

2. A method of producing gas plated metallized heatsensitive fibers, fabrics, and the like which comprises extruding a solution of a high molecular weight hydrocarbon polymer dissolved in a volatile solvent into the form of fine filaments, gathering said filaments into a continu-- ous length fiber, coating and impregnating said fibers with silicone resin to render the same heat-resistant, subjecting the drawn siliconized fiber to a heat-decomposable gaseous metal compound, and heat decomposing said gaseous metal compound in contact with said fiber to cause deposition of the metal constituent onto the filaments of the fiber to produce a metallized fiber which is soft and flexible.

3. A method of producing gas plated metallized heatsensitive fibers which comprises forming a fiber from a fiber-forming substance, impregnating and coating said fiber silicone resinous material which is stable at a temperature of 315 C. to render the fiber heat-resistant, subjecting the resultant fiber to an atmosphere containing a heat-decomposable gaseous metal compound, heating said heat-decomposable gaseous metal compound while in contact with said fiber to cause decomposition of said gaseous metal compound and deposition of said metal constituent, said metal compound being selected from the group consisting of metal carbonyls, hydrides, metal alkyls, metal halides, metal nitroxyl, and metal nitrosyl carbonyls.

4. A method of producing gas plated metallized heat-.

sensitive fibers which comprises forming a fiber from a fiber-forming substance, impregnating and coating said fiber silicone resinous material which is stable at a temperature of 315 C. to render the fiber heat-resistant, subjecting said fiber to an atmosphere containing a heatdecomposable gaseous carbonyl compound, heating said heat-decomposable gaseous metal compound while in contact with said fiber to cause decomposition of said gaseous metal carbonyl compound and deposition of said metal constituent.

5. A .gas plated metallized fiber produced in accordance with claim 1.

References Cited in the file of this patent UNITED STATES PATENTS 1,309,453 Bradley July 8, 1919 1,856,475 Frost May 3, 1932 2,367,152 Strab Jan. 9, 1945 2,466,434 Johannson Apr. 5, 1949 2,624,777 Abbott et al. Jan. 6, 1953 FOREIGN PATENTS 466,482 Great Britain May, 28, 1937 492,985 Great Britain Sept. 30, 1938 OTHER REFERENCES 79G8aseous Plating, Metal Finishing, October 1949, pp. 

1. A METHOD OF PRODUCING GAS PLATED METALLIZED HEATSENSITIVE FIBERS WHICH COMPRISES HEATING A FIBER-FORMING THERMOPLASTIC RESIN TO MELT THE SAME, SUBJECTING SAID MELTED RESIN TO EXTRUSION TO FORM A FIBER OF CONTINUOUS LENGTH, APPLYING A HEAT-RESISTANT SILICONE RESIN ONTO SAID EXTRUDED FIBER, AND SUBJECTING THE EXTRUDED AND SILICONE RESIN TREATED FIBER TO A HEAT-DECOMPOSABLE GASEOUS METAL COMPOUND,SAID GASEOUS METAL COMPOUND BEING BROUGHT IN CONTACT WITH SAID EXTRUDED FIBER WHILE HEATED TO A 